U.S. patent number 5,795,127 [Application Number 08/732,701] was granted by the patent office on 1998-08-18 for vertical shaft self-priming centrifugal pump.
This patent grant is currently assigned to Tecumseh Products Company. Invention is credited to David M. DeClerck.
United States Patent |
5,795,127 |
DeClerck |
August 18, 1998 |
Vertical shaft self-priming centrifugal pump
Abstract
A self-priming, vertical-shaft centrifugal pump having an
impeller design which creates an upward thrust and which is heavy
enough to carry an engine having a standard weight flywheel through
a compression stroke. The pump is comprised of a vertical-shaft
engine mounted onto a pump housing. The pump housing includes an
inlet chamber, a pumping chamber, and a separation chamber. The
shaft of the engine protrudes into the pumping chamber and is
mounted to an impeller which rotates within the pumping chamber.
The pump draws liquid into the pumping chamber from an inlet
communicating liquid entrained with gas to the pump. The impeller
uses centrifugal force to pump the liquid and gas mixture out of
the pumping chamber and into the separation chamber. In the
separation chamber, the entrained gas is removed from the liquid
and exhausted into the atmosphere, and the liquid is communicated
back into the pumping chamber to mix with additional liquid
entrained with gas until all of the entrained gas from the incoming
mixture is removed. To reduce the axial load on the bearings of the
engine, a pressure space is provided below the impeller shroud
which is in communication with the high pressure fluid expelled by
the impeller. The high pressure space pushes the impeller upward to
thereby lessen the load on the engine bearings. The shroud of the
impeller is sufficiently heavy to carry the engine through a
compression stroke so that an engine having a standard weight, less
expensive flywheel can be used.
Inventors: |
DeClerck; David M. (Utica,
MI) |
Assignee: |
Tecumseh Products Company
(Tecumseh, MI)
|
Family
ID: |
26675736 |
Appl.
No.: |
08/732,701 |
Filed: |
October 18, 1996 |
Current U.S.
Class: |
415/106;
417/364 |
Current CPC
Class: |
F04D
9/005 (20130101); F04D 13/02 (20130101); F04D
9/02 (20130101); F04D 29/0416 (20130101) |
Current International
Class: |
F04D
29/04 (20060101); F04D 13/02 (20060101); F04D
9/02 (20060101); F04D 9/00 (20060101); F04B
017/00 () |
Field of
Search: |
;417/424.1,364
;415/104,106,228 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gluck; Richard E.
Attorney, Agent or Firm: Baker & Daniels
Claims
What is claimed is:
1. A centrifugal pump, comprising:
an engine having a vertically disposed drive shaft rotatably
mounted within bearings;
a pump housing, said engine being attached to said pump housing
with said drive shaft extending downwardly into said pump
housing;
an impeller attached to said vertical drive shaft and rotatable
within said pump housing, said impeller and said shaft placing a
downward load on said engine bearings, said impeller having a
shroud, a central aperture, an outer circumference, and a plurality
of vanes, said shroud being perpendicular to said vertical drive
shaft and having a first side and an opposed second side, said
first side disposed adjacent said engine, said vanes being radially
disposed on said first side, said second side disposed adjacent
said pump housing with a pressure area disposed between said second
side and said pump housing;
whereby fluid being pumped passes through said central aperture in
said impeller and is expelled radially outward by said vanes to
said outer circumference of said impeller, fluid between said
central aperture and said outer circumference having a lower
pressure than fluid at said outer circumference, said pressure area
being in fluid communication with fluid at said outer circumference
and thereby having a relatively high pressure, said high pressure
area thereby placing an upward thrust on said second side of said
impeller to counteract against the downward load resulting from
said shaft and said impeller, the downward load on said engine
bearings thereby being reduced.
2. The centrifugal pump of claim 1, wherein said impeller vanes are
arcuate, said vanes pushing fluid radially outward as said impeller
rotates.
3. The centrifugal pump of claim 1 wherein said impeller has a
central hub area and a shroud, and the thickness of said shroud in
an axial direction at the outer periphery of said impeller is
greater than the thickness of said shroud at a position radially
intermediate the hub area and the outer circumference to thereby
peripherally weight said impeller.
4. A centrifugal pump, comprising:
an engine having a vertically disposed drive shaft and a
flywheel;
a pump housing, said engine being attached to said pump housing
with said drive shaft extending downwardly into said pump housing;
and
an impeller attached to said vertical drive shaft and rotatable
within said pump housing, said impeller having a plurality of
vanes, said vanes engaging a medium being pumped and forcing the
medium radially outward upon rotation of said impeller;
said impeller having a central hub area, said impeller, including a
shroud wherein the thickness of said shroud in an axial direction
at the outer circumference of said impeller is greater than the
thickness of said shroud at a position radially intermediate the
hub area and the outer circumference to thereby peripherally weight
said impeller.
5. The centrifugal pump of claim 4, wherein said impeller vanes are
arcuate.
6. The pump of claim 4 wherein said impeller includes a central
aperture therein, and fluid is pumped through said central aperture
and expelled radially by said vanes.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit under Title 35, U.S.C. .sctn.
119(e) of U.S. Provisional patent application Ser. No. 60/006,521,
entitled VERTICAL SHAFT SELF-PRIMING CENTRIFUGAL PUMP, filed on
Oct. 20, 1995.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to pumps, and more
particularly relates to centrifugal pumps.
2. Description of the Related Art
With certain centrifugal pumps, it is necessary to fill the pump
with the liquid that is to be pumped prior to operation. If a
centrifugal pump is run without first being filled with a liquid,
the internal parts of the pump requiring liquid lubrication can be
damaged or rendered unusable. This process of filling a centrifugal
pump with a liquid before operation is referred to as "priming" and
if the pump is above the level of the liquid to be pumped, the pump
must be "self-priming." Self-priming pump capability requires the
pump to be able to remove gases entrained with the liquid from a
suction inlet leading to the pump. If the gases are not totally
removed from the suction inlet, the pump will not be able to
function effectively and efficiently as there will be air pockets
in the incoming flow of liquid which will interrupt the flow of the
fluid being pumped.
The separation of the liquid and gas has typically been performed
in a separation chamber of the pump which employs gravity for
separation of the gas from the liquid. For example, U.S. Pat. No.
2,022,624 discloses a pump having a horizontal shaft engine,
wherein the fluid being pumped flows vertically or upward from the
impeller. The fluid is then at a height sufficiently high to allow
gravity to separate the gas from the liquid by having the liquid
flow downward and the gas flow upward.
However, given the mass production of vertical shaft engines, as
well as the more complicated mounting hardware associated with
horizontal shaft engines, vertical shaft engines are considerably
less expensive than horizontal shaft engines. Consequently, it
would be advantageous to have a self-priming pump which uses a
vertical shaft engine to separate the liquid from the gas. U.S.
Pat. No. 2,292,529 discloses a vertical shaft engine to power a
self-priming pump. However, with such a device the weight of the
engine and the impeller is entirely supported by the engine
bearings. This may result in either premature fatigue of the engine
bearings or may necessitate the use of specially designed bearings,
at additional expense, to support the axial load resulting from the
weight of the engine and impeller.
Moreover, typical centrifugal pumps employ two-stroke engines to
power the pump. Such engines use a heavy flywheel, at additional
expense, to carry the engine through its compression stroke.
SUMMARY OF THE INVENTION
The present invention is a self-priming pump which satisfies the
above-identified needs by using a vertical shaft engine to power
the pump, and an impeller design which creates an upward thrust
which counteracts the downward axial load of the engine and
impeller to thereby enable the vertical shaft engine bearings to
handle the axial load resulting from the impeller and engine. The
present invention also uses a weighted impeller so that an engine
having a standard weight, less expensive flywheel can be used.
The present invention is comprised of a vertical shaft engine
wherein an impeller is mounted to the shaft. When the shaft is
rotated, the impeller generates a centrifugal force which forces
the incoming fluid to the outer periphery of the housing
surrounding the impeller. The fluid flows horizontally outward from
the impeller and into a separation chamber. In the separation
chamber, the entrained gas is separated from the liquid and the
liquid in turn is put back into the impeller to mix with additional
liquid entrained with gas until substantially all gases are removed
from the inlet to the pump.
To reduce the axial load on the engine bearings, the impeller
includes a shroud placed on the side of the impeller opposite the
engine. A pressure space thereby exists between the bottom of the
shroud and the pump housing. The high-pressure liquid expelled by
the impeller is communicated to the pressure space. Since the
liquid in the pressure space has a higher pressure than the liquid
flowing across the top of the impeller, an upward thrust is created
which pushes the impeller upward and thereby lessens the downward
load on the engine bearings. This design reduces the load on the
bearings in magnitude because the impeller generates an upward
thrust to counteract against the downward axial load resulting from
the weight of the engine.
One advantage of the present invention is that the impeller design
reduces the axial load on the engine bearings by creating an upward
thrust to counteract the downward axial load of the engine and
impeller. The engine bearings are thereby able to better accept the
downward axial load resulting from the weight of the engine and
impeller.
Another advantage of the present invention is that the overall cost
of the self-priming pump is reduced through the use of a vertical
shaft engine having a standard weight flywheel.
The present invention, in one form, provides a centrifugal pump
comprising an engine, a pump housing, and an impeller. The engine
has a vertically disposed drive shaft rotatably mounted within
bearings and extending downwardly into the pump housing. The
impeller is attached to the vertical drive shaft and is rotatable
within the pump housing with the impeller and shaft placing a
downward load on the engine bearings. The impeller includes a
central aperture, an outer circumference, a shroud and a plurality
of vanes. The shroud is perpendicular to the drive shaft and
includes a first side and an opposed second side with the first
side disposed adjacent the engine. A plurality of vanes are
radially disposed on the first side. The second side is disposed
adjacent the pump housing with a pressure space disposed between
the second side and the pump housing. Fluid is pumped through the
impeller central aperture and is expelled radially outward by the
vanes disposed on the impeller to the outer circumference of the
impeller. Fluid between the central aperture and the outer
circumference has a lower pressure than fluid at the outer
circumference with the pressure area being in fluid communication
with the fluid at the outer circumference and thereby having a
relatively high pressure. The high pressure area thereby places an
upward thrust on the second side of the impeller to counteract
against the downward load resulting from the shaft and impeller.
The downward load on the engine bearings is thereby reduced.
The present invention, in another form thereof, provides a
centrifugal pump comprising an engine, a pump housing, and an
impeller. The engine has a vertically disposed drive shaft, a
standard weight flywheel, and is attached to the housing such that
the driveshaft extends downwardly into the pump housing. The
impeller is attached to the vertical drive shaft and is rotatable
within the pump housing. The impeller includes a plurality of vanes
which engage a medium being pumped and force the medium radially
outward upon rotation of the impeller. The impeller has a weight
sufficient to carry the engine through a compression stroke.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and advantages of this
invention, and the manner of attaining them, will become more
apparent and the invention will be better understood by reference
to the following description of an embodiment of the invention
taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is a partial sectional view of the present invention;
FIG. 2 is a bottom view of the impeller shown in FIG. 1;
FIG. 3 is a sectional view of the impeller taken along line 3--3 of
FIG. 2;
FIG. 4 is a partial sectional view of the pump housing taken along
line 4--4 of FIG. 5;
FIG. 5 is a top view of the pump housing shown in FIG. 1; and
FIG. 6 is an exploded perspective view of the invention shown in
FIG. 1.
Corresponding reference characters indicate corresponding parts
throughout the several views. The exemplification set out herein
illustrates one embodiment of the invention in one form and such
exemplification is not to be construed as limiting the scope of the
invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIGS. 1 and 6, the present invention is generally
depicted as vertical shaft pump 20. The primary mover, engine 22,
is shown having vertical shaft 24 to which impeller assembly 26 is
mounted. Engine 22 also includes housing 28 which encloses flywheel
30 (FIG. 1). Vertical shaft engines are commonly available in the
art and a 3.8 horsepower "Vantage" Model No. TVS90, manufactured by
Tecumseh Products Company, is provided as an example. Engine 22 is
mounted to pump housing 32 such that shaft 24 vertically extends
from engine 22 into pump housing 32.
Pump housing 32 is described with more complete detail with
reference to FIGS. 4 and 5. Pump housing 32 is comprised of three
distinct chambers, pump inlet chamber 34, pumping chamber 36, and
separation chamber 38. Pump inlet chamber 34 is provided with a
pump inlet 40 to which a suction hose or other means (not shown)
for providing a liquid to be pumped is attached. Pump inlet chamber
34 communicates with, and is provided adjacent to, the base of
pumping chamber 36. As shown in FIGS. 1 and 6, the outside of pump
inlet 40 is provided with a suction flange 42, flapper assembly 44
and fastening screws 46. Suction flange 42 allows for threaded or
other suitable means for connecting a suction hose (not shown),
whereas flapper assembly 44 serves as a check valve which prevents
backflow of the fluid being pumped. As best shown in FIG. 1,
flapper assembly 44 consists of elastomeric member 48 to which
metal plates 50 are affixed via fastener 52. Flapper member 48
moves into the pump housing when sufficient suction pressure is
present, and is elastically biased to the position shown in FIG. 1
otherwise to thereby prevent the fluid from flowing back through
pump inlet 40.
Pumping chamber 36 is above pump inlet chamber 34 and serves as the
chamber in which impeller assembly 26 rotates. Central aperture 54
is provided in bottom wall 56 of pumping chamber 36 for
communicating liquid from pump inlet chamber 34 into pumping
chamber 36. The liquid to be pumped therefore enters pumping
chamber 36 through central aperture 54 of bottom wall 56 and
thereby into center aperture 58 of impeller assembly 26. Rotation
of impeller assembly 26 generates a centrifugal force which causes
the liquid to move to the outer circumference of impeller assembly
26 whereat the liquid is redirected by curved wall 60. The liquid
being pumped then exits pumping chamber 36 through diffuser passage
62.
In specific reference to FIG. 4, separation chamber 38 is shown
directly adjacent and in communication with diffuser passage 62.
Given that engine 22 and shaft 24 are mounted vertically, and
impeller assembly 26 is therefore horizontal, the liquid being
pumped exits impeller assembly 26 in a horizontal direction, passes
through diffuser passage 62 in a horizontal direction, and enters
separation chamber 38 in a horizontal direction. Since separation
chamber 38 extends from the base of pump inlet chamber 34 to a
distance substantially above the top of pumping chamber 36, and
diffuser passage 62 communicates with separation chamber 38 at the
approximate halfway point of the separation chamber 38, the liquid
being expelled by impeller assembly 26 through diffuser passage 62
enters separation chamber 38 and is immediately pulled toward the
base of separation chamber 38 due to gravity.
Quiet zone 64 is the internal space of separation chamber 38
wherein the liquid falls after being expelled from diffuser passage
62. In quiet zone 64, the difference in densities between the gas
and the liquid allows the gas to rise and separate from the liquid
and exit pump 20 through pump outlet 66. The liquid then reenters
pumping chamber 36 to mix with additional liquid entrained with gas
which enters through the aforementioned suction hose. Once all the
entrained gas has been removed from the incoming liquid, the flow
rate of pump 20 will naturally accelerate, forcing more liquid into
separation chamber 38 and ultimately into tower 68 to allow for the
liquid to exit pump 20 through pump outlet 66 (FIG. 6).
As shown in FIGS. 1 and 6, impeller assembly 26 is mounted to shaft
24 and rotates within pumping chamber 30. Impeller assembly 26 is
comprised of adapter 70, impeller 72, and seal assembly 74 (FIG.
6). Adapter 70 is mounted to engine 22 by bolts 76 or other
suitable mounting means. Adapter 70 is used to provide a top
surface for pumping chamber 36 so that the bottom of engine 22 is
not in immediate contact with the pumping fluid. In order to
effectively seal the joint between impeller 72 and shaft 24, seal
assembly 74, which is comprised of washers 78, O-ring 80, and
sealing elements 82, is provided.
Referring now to FIGS. 2 and 3, impeller 72 is shown having arcuate
vanes 84 provided thereon to push the liquid as the impeller is
rotating. In the exemplary embodiment, an impeller having one
shroud 86, commonly referred to as a "semi-open impeller", is used.
Shroud 86 is provided on impeller 44 on the side of impeller 72
opposite engine 22 in order to reduce the downward axial load on
engine bearing 88 (FIG. 1). The downward axial load results from
engine 22, engine flywheel 30, shaft 24, and impeller assembly 26.
A substantial axial load is therefore placed on bearing 88 of
engine 22, which is typically in excess of the load capacity of
standard engine bearings. By placing shroud 86 on the side of the
impeller opposite engine 22, the downward axial load is
counteracted by the upward thrust generated by impeller 26 as
described with greater detail herein. The axial load on bearing 88
of engine 22 is thereby reduced.
During the operation of pump 20, liquid enters between vanes 84 of
impeller 72 through center aperture 58 in the hub area of shroud
86. The centrifugal force generated by impeller 72 increases the
pressure and velocity of the liquid as the liquid travels to the
outer circumference of impeller 72. Maximum pressure and velocity
is attained at the outer circumference of impeller 72. The area
between the bottom of shroud 86 and the pump housing (area 90 shown
in FIG. 1) is in communication with the high pressure liquid at the
outer circumference of impeller 72 and is therefore a high pressure
area. The area above shroud 86 between center aperture 58 and the
outer circumference of the impeller has a lower pressure than area
90. The pressure within area 90 therefore pushes upward against
shroud 86 and therefore creates an upward thrust which pushes
impeller 72 upward toward engine 22, and in the direction opposite
to the downward axial load created by engine 22 and impeller
assembly 26.
The net result of this design is that bearing 88 of engine 22 is
able to operate efficiently due to the balancing of the downward
axial load and the upward thrust generated by impeller 72. Impeller
72 is also provided with mounting boss 92 forming a hub which
serves as a seat for seal assembly 74 which is itself mounted
annularly about the circumference of shaft 24. Finally, impeller
assembly 26 is secured to shaft 24 by connecting bolt 94.
In order for the present invention to be able to employ a
conventional vertical shaft engine having a standard weight
flywheel, additional mass is added to shroud 86 of impeller 72, by
thickening shroud mainly at the outer circumference thereof (FIG.
3). Impeller 72 therefore has sufficient mass to carry four-stroke
engine 22 through a compression stroke during which engine 22 is
not generating force. This is similar to the operation of a lawn
mower wherein the vertical shaft engine has a blade rotating
therewith. Otherwise, a heavy flywheel, at added expense, would
have to be used to provide the necessary mass. Impeller 72 includes
slots 96 (FIG. 2).
In operation, vertical shaft pump 20 is stationed above the level
of the liquid to be pumped. A suction hose or other means is
connected to pump 20 to communicate the liquid to be pumped to pump
inlet 40. A similar hose or pumping conduit is connected from pump
outlet 66 to the area or container receiving the pumped liquid.
Pump 20 will initially be filled through fill port 98 to a level
sufficient to fill pumping chamber 36, but low enough to be below
pump outlet 66. Fill port 98 will then be closed using threaded
bung 100. When engine 22 is started, shaft 24 will rotate which, in
turn, will rotate impeller 72 within pumping chamber 36. The
rotation of impeller 72 will create a centrifugal force within
pumping chamber 36 which will draw the liquid toward the periphery
of impeller 72 to curved wall 60 and ultimately into diffuser
passage 62. As the liquid exits pumping chamber 36, a continuous
supply of liquid enters through the suction hose and pump inlet
chamber 34.
From diffuser passage 62, the liquid will pass into quiet zone 64
of separation chamber 38 wherein the lessening velocity of the
liquid and the difference in densities between gas and liquid will
allow the gas to rise and the liquid to fall. The gas will
ultimately leave vertical shaft pump 20 through pump outlet 66 of
tower 68, whereas the liquid will reenter pumping chamber 36. The
separated liquid will then mix with additional liquid having
entrained gas therein and enter pumping chamber 36 through central
aperture 54 of bottom wall 56. As before, centrifugal force will
draw the liquid to the outer periphery of impeller 72 to curved
wall 60 and ultimately to diffuser passage 62. Once substantially
all the entrained gas is removed, the flow rate of pump 20 will
accelerate, thereby forcing more liquid into separation chamber 38
and ultimately into tower 68 where the liquid will be able to exit
pump 20 through pump outlet 66.
While this invention has been described as having a particular
design, the present invention can be further modified within the
spirit and scope of this disclosure. This application is therefore
intended to cover any variations, uses, or adaptations of the
invention using its general principles. Further, this application
is intended to cover such departures from the present disclosure as
come within known or customary practice in the art to which this
invention pertains, and which fall within the limits of the
appended claims.
* * * * *